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United States Patent |
6,183,072
|
Altendorf
|
February 6, 2001
|
Seal using gasket compressed normal to assembly axis of two parts
Abstract
An inkjet storage container sealing mechanism is comprised of a cover, a
receptacle, a gasket compressed normal to its insertion and a support
member to maintain a seal that is resistant to ink and air penetration.
The receptacle has sidewalls that form an opening. A gasket is stretched
over a portion the cover, then the gasket and the portion of the cover is
inserted into the opening of the receptacle. The gasket forms a seal
between the cover and the receptacle. The compressive forces acting on the
gasket to form the seal do not contribute additional forces to a
mechanical joining mechanism, which attaches the cover to the receptacle.
The support member prevents the sidewalls of the receptacle from
deflecting to help maintain the seal.
Inventors:
|
Altendorf; John M. (Corvallis, OR)
|
Assignee:
|
Hewlett-Packard Company (Palo Alto, CA)
|
Appl. No.:
|
070132 |
Filed:
|
April 29, 1998 |
Current U.S. Class: |
347/85 |
Intern'l Class: |
B41J 002/175 |
Field of Search: |
347/85,86,87
|
References Cited
U.S. Patent Documents
4568954 | Feb., 1986 | Rosback | 347/86.
|
4771298 | Sep., 1988 | Lee et al. | 347/68.
|
4841310 | Jun., 1989 | Hoffman | 346/75.
|
5103243 | Apr., 1992 | Cowger | 347/87.
|
5365262 | Nov., 1994 | Hattori et al. | 347/87.
|
5408256 | Apr., 1995 | Keen et al. | 347/87.
|
5435961 | Jul., 1995 | Micciche | 264/319.
|
5448275 | Sep., 1995 | Fong | 347/87.
|
5610644 | Mar., 1997 | Timm, Jr. et al. | 347/87.
|
5619239 | Apr., 1997 | Kotaki et al. | 347/86.
|
5642144 | Jun., 1997 | Plotkin | 347/87.
|
5659345 | Aug., 1997 | Altendorf | 347/87.
|
5663753 | Sep., 1997 | Story et al. | 347/86.
|
5666146 | Sep., 1997 | Mochizuki et al. | 347/86.
|
5671001 | Sep., 1997 | Elliot et al. | 347/87.
|
5680164 | Oct., 1997 | Miller et al. | 347/87.
|
5684521 | Nov., 1997 | Salter et al. | 347/87.
|
5719609 | Feb., 1998 | Hauck et al. | 347/85.
|
5917523 | Jun., 1999 | Baldwin et al. | 347/85.
|
5958342 | Sep., 1999 | Gamble et al. | 422/100.
|
Foreign Patent Documents |
633138A2 | Jan., 1995 | EP | .
|
98/55322 | Dec., 1998 | WO | .
|
Other References
"Injection Molds And Molding-A Practical Manual", Second Edition; by:
Joseph B. Dym; Copyright 1987 by Van Nostrand Reinhold Company, Inc; 5
pages.
|
Primary Examiner: Le; N.
Assistant Examiner: Nghiem; Michael
Attorney, Agent or Firm: Myers; Timothy F.
Claims
What is claimed is:
1. An inkjet storage container sealing mechanism comprising:
a receptacle having an inside surface, an outside surface and a peripheral
lip surrounding an opening in said receptacle, a gasket seal area inside
said opening; and a beveled edge surrounding said opening and formed into
said receptacle and extending to said gasket seal area;
a cover having an inside surface, an outside surface, and a flange member
disposed on said cover outside surface, said cover adapted to fit said
opening with said cover outside surface facing said receptacle inside
surface, and said flange member adapted to mate with said peripheral lip;
and
a gasket surrounding said opening and disposed between said receptacle
inside surface and said cover outside surface whereby a direction of
compression of said gasket is normal to said receptacle inside surface and
normal to said cover outside surface and the direction of compression is
normal to the direction of insertion of said cover into the opening in
said receptacle whereby the normal compression of said gasket is done
gradually during an insertion of said cover into said opening of said
receptacle.
2. The inkjet storage container sealing mechanism of claim 1 wherein said
cover and said receptacle are joined using heat staking.
3. The inkjet storage container sealing mechanism of claim 1 wherein said
cover and said receptacle are joined using a snap lock mechanism between
said cover and said receptacle.
4. The inkjet storage container sealing mechanism of claim 1 wherein said
cover and said receptacle are attached using at least one screw to join
said cover to said receptacle.
5. The inkjet storage container mechanism of claim 1 wherein said gasket
further comprises a plurality of individual comers, each individual comer
having an inner radius and an outer radius, said inner radius formed to
outline said outside surface of said cover, said outer radius shaped to
conform to said inside surface of said receptacle.
6. The inkjet storage container sealing mechanism of claim 1 wherein said
gasket is constructed having a uniform diameter.
7. The inkjet storage container sealing mechanism of claim 1 wherein said
cover further comprises an ink inlet, through which ink is introduced into
the inkjet storage container.
8. The inkjet storage container of claim 1 wherein said gasket seal area
has essentially zero degrees of draft.
9. An inkjet storage container comprising:
a cover including;
at least two snap lock mechanisms, and
a gasket receiving area;
a receptacle including;
a plurality of sidewalls,
at least two sidewall protrusions disposed on said plurality of sidewalls,
said at least two snap lock mechanisms interlockable into said at least
two sidewall protrusions,
an opening defined by said plurality of sidewalls,
a gasket seal area inside said opening, and
a beveled edge surrounding said opening and formed into said receptacle and
extending to said gasket seal area;
a gasket disposed on said cover such that said gasket receiving area of
said cover is circumscribed by said gasket, and said gasket inscribed
within said gasket seal area of said receptacle, said gasket compressed
between said cover and said opening of said receptacle in a direction
normal to said receptacle gasket seal area and said gasket receiving area,
whereby the compression of said gasket is done gradually during insertion
of said cover subassembly into said opening of said receptacle and the
direction of compression is normal to the direction of insertion of said
cover into the opening in said receptacle; and
a support structure on said cover circumscribing said plurality of
sidewalls of said receptacle after assembly whereby said seal is
maintained.
10. The inkjet storage container of claim 9 wherein said gasket receiving
area has essentially zero degrees of draft and wherein said gasket seal
area has essentially zero degrees of draft.
Description
BACKGROUND OF THE INVENTION
This invention generally relates to inkjet printing. More particularly,
this invention relates to the sealing and assembly of a container used to
store and deliver ink to an inkjet printhead, by which the invention
provides a robust solution to needs for today's products, such as
replacing or repairing ink delivery systems.
Many printers today use inkjet pens to produce recorded media. The inkjet
pens have a container used to store and deliver ink to the printhead. The
containment of the ink is usually done at a partial vacuum in the range of
0.5 to 9.0 inches of water column to prevent leakage of ink from the
printhead. It is undesirable to allow ink to penetrate a seal between
different pen parts that create this containment body. Likewise, it is
also undesirable to allow air to intrude the containment body through the
seal. In addition, the seal technique used should not be permitted to
degrade the ink within the container, such as by the seal corroding due to
a reaction with the ink. To allow for easy maintenance of assembly
processes, it is desirable to have the sealing function be highly
consistent and reliable in its manufacture. An additional feature desired
in a seal design is the ability to seal, unseal and reseal without
degradation of the seal's properties. This feature would permit new
processes to be used to repair or modify an inkjet pen.
One current approach to sealing members on inkjet pens is to use an
adhesive.
However, most adhesives and their resultant seals degrade when exposed to
the ink. In addition, many adhesives have also been shown to contaminate
the ink. Other manufacturing problems are related to the time it takes
adhesives to cure, thus limiting throughput, and the inconsistency of
seals on separate containers due to the variation of adhesive formulations
from lot to lot. Although using heat can accelerate the curing time of an
adhesive, the heat often causes other parts of the pen to become damaged.
In addition, damage to the sealing members occurs when the adhesive joint
is broken, thus preventing one from repairing a malfunctioning inkjet pen.
Ultrasonic welding is a second approach used on contemporary inkjet pens to
seal members. This technique requires the materials of the two parts being
sealed to be ultrasonically compatible which is not always desirable or
even possible for a given application. The high frequency energy, used to
heat and melt the plastic, often causes damage to other parts of the pen.
To perform the ultrasonic welding properly, the parts need to be precisely
supported during the weld thereby requiring expensive tooling fixtures. In
addition, to ensure consistency and quality of the weld joints, there must
be significant planarity between the welding surfaces, which requires
tight part tolerances, thus making them more expensive. Many times energy
directors are molded into the plastic to increase the likelihood of
welding a good seal. These energy directors are usually delicate part
features that are easily damaged. Once an ultrasonic seal is broken, it is
virtually impossible to reseal properly and this prevents repairing a
malfunctioning inkjet pen.
A third approach used is a face seal gasket between the mating parts. The
face seal gasket requires that the mechanical joining function of the
mating parts react to a constantly applied load from the face seal gasket.
This force requires the surfaces on each side of the face seal gasket be
smooth and rigid, thus increasing the part cost. In addition, there must
be a continuous attachment mechanism or one that has frequent points of
attachment to keep the joining surfaces flat. If the attachment mechanisms
are exposed to the ink, they may degrade. In addition, if there is a
preexisting stress in an attachment point, it may fail after a prolonged
period in which it has been subjected to the gasket force, thus causing an
early failure of the seal.
There is a need for an attachment and sealing process that is suitable for
low cost, high volume manufacturing processes such as those used in
assembling inkjet pens. A new seal design must allow for less expensive
components, more efficient processes, and high volume manufacturing that
provides better consistency, quality and reliability of the finished
product. The ability to make repeated seals and reseals without
degradation would allow an inkjet pen to be repaired or modified.
Furthermore, a new seal design also needs to: allow for parts having
looser tolerances; withstand attack from many different types of ink;
allow for the attachment joint to not be in contact with the ink; and be
virtually independent to the use of different plastic molding material.
Other concerns a new seal design should address are: saving capital
tooling costs required to build production lines, minimizing the size of
production lines, and preventing process induced damage to other parts of
the pen which might go undetected during manufacturing and later become
field failures.
SUMMARY OF THE INVENTION
An inkjet storage container sealing mechanism is comprised of a cover, a
receptacle, a gasket compressed normal to its insertion and a support
member to maintain a seal that is resistant to ink and air penetration.
The receptacle has sidewalls that form an opening. The gasket is stretched
over a portion of the cover; then the gasket and the portion of the cover
are inserted into the opening of the receptacle. The gasket forms a seal
between the cover and the receptacle. The compressive forces acting on the
gasket to form the seal do not contribute additional forces to a
mechanical joining mechanism, which attaches the cover to the receptacle.
The support member of the cover prevents the sidewalls of the receptacle
from deflecting. This support member helps maintain the gasket seal.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 schematically depicts an exemplary embodiment of a printing system.
FIG. 1A is an isometric drawing showing an exemplary inkjet cartridge using
heat stake attachment of members.
FIG. 1B is a schematic cross-sectional drawing illustrating an exemplary
inkjet cartridge employing the preferred embodiment of the invention along
the AA view of FIG. 1A.
FIG. 2A is a drawing illustrating a non-uniform cross-sectional gasket such
as that used in FIG. 1B, between two members of the cartridge where the
gasket is specially molded to conform to the member parts.
FIG. 2B is a drawing illustrating a uniform cross- section gasket such as
that used in FIG. 1B, between two members of the cartridge in which the
members are molded to conform to the uniform gasket.
FIG. 3A is a drawing illustrating the assembly of the two members of the
cartridge of FIG. 1B with a gasket and a heat staking method of attaching
the two members.
FIG. 3B is a drawing illustrating the assembly of the two members of the
cartridge of FIG. 1B with a gasket and a heatstaking method of attaching
the two members with an alternative design for limiting sidewall
deflection.
FIG. 3C is a drawing illustrating the assembly of the two members of FIG.
1B with a gasket and the preferred attachment scheme using a snap lock
mechanism method of attaching the two members.
FIG. 3D is a drawing illustrating the assembly of the two members of FIG.
1B with a gasket and an alternative attachment scheme using a screw method
of attaching the two members.
FIG. 4A illustrates the receiving detail in one member of the ink jet
cartridge used in a snap joint attaching mechanism.
FIG. 4B illustrates the snap detail in one member of the ink jet cartridge
used in a snap joint attaching mechanism.
FIG. 4C illustrates the receiving and snap details when mating the two
members.
FIG. 4D illustrates an alternative snap lock mechanism.
FIG. 5A-5C schematically illustrate a process of disabling an existing ink
delivery system and for providing a new ink delivery system.
FIG. 5A illustrates the dis-attachment of an inkjet cartridge.
FIG. 5B illustrates removal of an old ink delivery system from an inkjet
cartridge.
FIG. 5C illustrates the insertion of a new ink delivery system into an
inkjet cartridge.
FIG. 5D illustrates the re-attachment of a new ink delivery system to an
inkjet cartridge.
FIG. 6A illustrates an electronically controlled valve ink delivery system
connected to an inkjet cartridge.
FIG. 6B illustrates a gravity regulated ink delivery system connected to an
inkjet cartridge.
FIG. 6C illustrates a removable type ink delivery system using the gasket
sealing mechanism of the preferred embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 schematically depicts an exemplary embodiment of a printing system
16 for which the present invention can be employed. Printing system 16
includes an inkjet cartridge 10 that is fluidically connected to an ink
supply 70 via conduit 68. Inkjet cartridge 10 includes a printhead 20 that
receives signals from printing system control electronics 30 and
selectively deposits ink onto media (not shown) in response.
In this exemplary embodiment, print cartridge 10 is an assembly including a
receptacle 22 and a cover 28 which comprise printhead housing 36.
Receptacle 22 has an inner cavity 32 that is fluidically connected to
printhead 20. Inner cavity 32 forms an opening 18. Cover 28 is positioned
in opening 18. Cover 28 includes an ink inlet 104 that is fluidically
coupled to conduit 68. Cover 28 also includes a valve 72 that fluidically
couples ink inlet 104 to inner cavity 32.
The combination of ink supply 70, conduit 68, and cover 28 can be referred
to as an ink delivery system (IDS) for printhead 20. When valve 72 is
open, ink flows from ink supply 70, through conduit 68, to valve 72, and
into inner cavity 32. During operation of printhead 20, a pressure
regulator actuator 48 opens and closes valve 72 in response to pressure
changes in inner cavity 32 to regulate the pressure of ink supplied to
printhead 20. It is important that the pressure in inner cavity 32 be
maintained within a printhead operating range (typically a negative 0.5 to
9.0 inches of water) to assure a stable negative operating pressure in
inner cavity 32.
If cover 28 has a pressure regulator actuator attached to it, it is
difficult to use ultrasonic welding between cover 28 and receptacle 22.
This difficulty is caused by the difficulty in directing the ultrasonic
energy only to the sealing surface and not to the regulator portions. If
the regulator parts are damaged during ultrasonic welding, the damage is
difficult to detect. Thus, parts may be only slightly damaged yet still
function when the unit is tested. The damaged parts may prevent optimum
performance or fail later causing consumer displeasure and warranty
replacements. An additional concern with using ultrasonics is that the
cover 28 and receptacle 22 must both be made of a material that is
compatible with each other to form an ultrasonic seal.
When a conventional adhesive is used for sealing the cover 28 and
receptacle 22, the amount of time needed to cure the adhesive prevents the
process from being practical for mass production. Heating the adhesive
during curing can shorten the process time needed to cure the adhesive.
The heat, if not carefully controlled, can melt, deform or damage portions
of the regulator mechanism. An additional concern with an adhesive is that
the cover 28 and receptacle 22 must both be made of a material that is
compatible with the adhesive used. Often times, the design criteria for
the cover 28 and receptacle 22 will require that they be made of different
materials, thus limiting the type of adhesive, indeed if any acceptable
choices of adhesive are available that also are compatible with the ink
stored in the container.
One aspect of the present invention concerns a means of sealing an ink
containment vessel such as inkjet cartridge 10. In the preferred
embodiment, the sealing means is a compressed gasket 120 that is located
between cover 28 and receptacle 22. This sealing means can be accomplished
without costly adhesive curing processes or ultrasonic welding processes
that may damage the materials used to fabricate inkjet cartridge 10.
Another aspect of the invention concerns a means of changing the ink
delivery system to accommodate different printing requirements. In the
preferred embodiment, gasket 120 provides an advantageous way of changing
the ink delivery system without damage to receptacle 22. This can be done
by disabling the ink delivery system and then connecting a new ink
delivery system to printhead 20. In the preferred embodiment, this is done
by removing cover 28 from receptacle 22 and then connecting a new ink
delivery system to inner cavity 32. Before discussing this second aspect
of the invention, it is useful to discuss the first aspect with respect to
FIGS. 1A-4D.
FIG. 1A depicts an isometric view of an ink containment vessel such as
inkjet cartridge 10 that includes only details pertaining to the assembly
of inkjet cartridge 10. A cover such as cover 28 is secured to a
receptacle such as receptacle 22 via attachment features 24. In the
preferred embodiment, attachment features 24 comprise snap features,
however, other embodiments might use heat stake pins as in FIGS. 1A and
1B, or screws, staples, or clips which are discussed later.
FIG. 1A shows the outside of an inkjet cartridge 10. Cover 28 and
receptacle 22 (either piece comprised of polyphenylene sulfide, liquid
crystal polymer, syndiotactic polystyrene or polyethylene napthalate, but
preferably polyphenylene sulfide material in the preferred embodiment) are
attached using attachment features 24. Ink inlet 104 is used to connect
the inkjet cartridge 10 with the rest of the printing system 16. The ink
is expelled from ink cartridge 10 through printhead 20. As ink is
expelled, air enters screw air vent 26 to operate the pressure regulator
actuator 48.
FIG. 1B is a cross-sectional schematic representation of the exemplary
inkjet cartridge 10 of FIG. 1A along the AA perspective that utilizes the
preferred embodiment. The cover 28 is sealed to receptacle 22 using a
gasket 120. Gasket 120 is compressed in a direction normal to the
direction in which cover 28 is assembled to receptacle 22. Support member
110 prevents the sidewall deflection of receptacle 22 ensuring that gasket
120 is not under-compressed, which would compromise the fluid seal between
the cover 28 and receptacle 22. Maintaining a proper seal is critical to
the stable operation of inkjet cartridge 10.
As described with respect to FIG. 1, inkjet cartridge 10 includes a means
of maintaining a stable operating pressure in inner cavity 32. Valve 72 is
formed by a seal between a lever 126 and a valve outlet portion 108. Lever
126 is pivotally mounted to cover 28 such that the rotational motion of
lever 126 opens and closes valve outlet portion 108. An expandable bag 124
is located adjacent to lever 126. Expandable bag 124 has an inner surface
that is fluidically connected to outside atmosphere through screw air vent
26. As the printhead 20 ejects ink droplets, the pressure in inner cavity
32 become more negative. In response, expandable bag 124 expands, pressing
on lever 126 to allow ink to flow into inner cavity 32 as discussed with
respect to FIG. 1.
The inkjet cartridge 10 when assembled holds an ink supply 122. Ink supply
122 is refilled by the use of an fluid regulator type ink delivery system
(IDS), for pressure regulator actuator 48, comprised of expandable bag
124, moment arm 128, valve moment arm 126, spring 132 and screw air vent
26. When ink supply 122 is reduced, expandable bag 124 expands causing
valve moment arm 126 to rotate causing valve seat 108 to open which allows
ink in from an ink inlet 104. Ink is drawn out of the inkjet cartridge
through ink filter 134 and out of printhead 20 when printing onto an
external surface.
In the preferred embodiment, the inkjet cartridge 10 is assembled by
mounting the gasket 120 so that it circumscribes a gasket receiving area
90 of cover 28. To make assembly of cover 28 into receptacle 22 easier,
the gasket 120 can be pre-coated with polyethylene glycol (PEG).
Alternatively, the seal area of the receptacle 22 can be pre-coated with
PEG. An alternative approach is to use a gasket that is molded with a
lubricant (such as PEG, or Teflon, preferably Teflon) to reduce the amount
of process steps in manufacturing and to provide consistent results. After
gasket 120 is mounted on cover 28, cover 28 is inserted into receptacle
22. During insertion, gasket 120 is compressed by features of cover 28 and
receptacle 22. At the completion of insertion, gasket 120 is compressed in
a direction that is normal (orthogonal) to the direction of insertion.
This form of compression causes gasket 120 to form a seal between cover 28
and receptacle 22 whereby the compressive force from gasket 120 is
directed to the sidewalls of receptacle 22 and cover 28. Further, this
form of compression prevents compression forces from acting in a direction
that would separate cover 28 and receptacle 22, thereby minimizing stress
on attachment features 24.
Gasket 120 can be fabricated by two different methods to provide an
effective seal. A uniform cross-sectional gasket is the easiest to
fabricate, however, the design of the molded cover 28 and receptacle 22
must accommodate the gasket shape. Often times, for other design
decisions, the use of a uniform cross-sectional gasket is not desired. In
these cases, a non-uniform cross-sectional gasket can be made to precisely
mate with existing molded parts of cover 28 and receptacle 22.
FIG. 2A shows the detail of how a non-uniform gasket 44 is made to conform
to the dimensions of cover 28 and receptacle 22. Non-uniform gasket 44 has
for each corner an inner radius 42, which is shaped to fit the curvature
of cover 28. The corner also has an outer radius 40, which is shaped to
fit the curvature of receptacle 22. By using non-uniform gasket 44, the
seal formed by compression of the gasket can be performed with parts that
have a preexisting or required physical design.
Alternatively, FIG. 2B shows the detail of uniform gasket 46, which is
molded such that it has a consistent uniform cross-sectional profile. The
advantage of this approach is a simpler tool design for the molding of
uniform gasket 46. This approach is possible if cover 28 and receptacle 22
can be molded to accept uniform gasket 46.
Gasket 120, representing either uniform gasket 46 or non-uniform gasket 44,
has compressive forces that do not interact with the attachment of cover
28 to receptacle 22, and several alternative methods for this attachment
exist. In order to prevent excessive compression or non-compression during
periods of unforeseen stress (i.e. dropping, squeezing, etc.) the cover 28
has molded into it a flange support member 110 to limit deflection of the
sidewalls of receptacle 22. The attachment method and support member 110
can be accomplished several ways of which FIGS. 3A through 3D show
representative samples. Those skilled in the art will appreciate that
different methods of attachment for the cover 28 and receptacle 22 could
be used and still meet the spirit and scope of the invention.
FIG. 3A shows an embodiment in which the receptacle 22, having an inside
surface 52, an outside surface 54, a peripheral lip 56 with heat stake
posts 80 that are formed to hold cover 28 in place. Cover 28 has an inside
surface 60 and an outside surface 58. The heat applied to heat stake posts
80 is localized and very temporary, thus preventing the heat related
problems that occur with a heat curing adhesive. Also shown is a beveled
edge 50 on receptacle 22 that helps to slowly compress gasket 120 as cover
28 is inserted into receptacle 22. Gasket 120 contacts gasket receiving
area 90 on cover 28 and gasket seal area 92 on receptacle 22. Gasket
receiving area 90 and gasket seal area 92 are molded to have essentially
zero degrees of draft. This lack of inclination keeps the compressive
forces applied directly inward to the gasket 120 and limits the forces
applied to the gasket that are not directed inward to the gasket 120 to
prevent its movement after the inkjet cartridge 10 is assembled. The
support member 110, in this exemplary embodiment, is formed as a flange
around the outside surface 58 of cover 28.
FIG. 3B shows an alternative embodiment for a heat stake attachment scheme
in which an additional support member 62 is formed in cover 28 such that
it also supports holding gasket 120 to prevent gasket 120 from becoming
dislodged during the manufacturing process. Support member 110 prevents
outward flexing of the sidewalls of receptacle 22. Heat stake post 80 is
molded into receptacle 22.
FIG. 3C shows the preferred embodiment using a snap lock mechanism 94 for
attachment. Further detail of the snap lock is shown in FIGS. 4A-4C.
Receptacle 22 is molded to provide a barrier to gasket 120 and to provide
a stop 63 for support member 110 that is molded into cover 28.
FIG. 3D shows an alternative embodiment in which a screw 98 is used to
attach cover 28 to receptacle 22. Support member 110 is used to limit
sidewall deflection of receptacle 22 thus maintaining a seal with gasket
120 when external forces are applied to the inkjet cartridge 10.
FIG. 4A shows the receiving portion of the snap lock mechanism 94 used in
FIG. 3C. The receiver area 88 is molded into first member 28. An incline
87 is used to slowly glide the snaps (86 on FIG. 4B) until the snaps 86
rest on shelf 89. FIG. 4B shows the snap portion of the snap lock
mechanism 94 with snaps 86 molded into second member 22. FIG. 4C shows the
receiver area 88 and snap 86 when they are mated.
FIG. 4D illustrates an alternate snap lock mechanism 94 where a snap 86 is
molded as part of cover 28. This snap 86 mates into a receiver area 88 of
receptacle 22, securing cover 28 to receptacle 22. Two or more snap lock
mechanisms 94 are molded into cover 28 as required. Those skilled in the
art will appreciate that other snap feature shapes are possible which
could latch on the inside of receptacle 22 or the outside of receptacle 22
as illustrated and still meet the spirit and scope of the invention.
In regard to FIGS. 5A-5D, a method for modifying the ink delivery system of
printing system 16 (FIG. 1) is described. This enables printing system 16
to accommodate a variety of spatial configurations and ink use rate
requirements. The ink delivery system is replaced by disabling the first
ink delivery system and connecting a second ink delivery system to
printhead housing 36.
In the preferred embodiment, a first ink delivery system is disabled by
unsealing and removing cover 28 from receptacle 22 as depicted by FIGS. 5A
and 5B. Specifically, FIGS. 5A-5D illustrate a method to remove and
replace an ink-delivery subassembly (IDS), such as the regulator type
shown in FIG. 1B and represented in FIGS. 5A and 5B as a box and described
as old IDS 96. Therefore, if an IDS is defective, the print cartridge can
be repaired. In addition, new designs, which have new features or
benefits, can replace the existing IDS. Having this flexibility allows the
inkjet cartridge 10 to be manufactured for high volumes, and at the same
time, accommodate the printhead 20 in receptacle 22 for use in lower
volume applications.
As indicated by FIG. 5A, the attachment features 24 (FIG. 1A) are first
disabled. In the case wherein the attachment features are heat stake posts
80 as depicted by FIG. 3B, the heat stake posts 80 may be sheared or
otherwise broken. Next, cover 28 is removed in a direction that is
substantially perpendicular to a plane defined by gasket 120. In FIG. 5B,
this cover motion is used to remove the old IDS 96, further comprising
cover 28, gasket 120, and ink inlet 104, from the printhead housing 36,
which further comprises a gasket seal area 92, printhead 20 and receptacle
22, which has an inner cavity 32 with opening 18. As this motion is done,
the seal formed by gasket 120 with respect to receptacle 22 and cover 28
is broken.
Next in FIG. 5C, a new IDS, or a portion 97 of it, of a similar or
different type than old IDS 96, discussed in FIGS. 1 and 1B, is oriented
such that it can be positioned into the printhead housing 36 through
opening 18. In the preferred embodiment, the same gasket arrangement is
used to provide the seal as was discussed with respect to FIGS. 1B and
2A-2B. However, provided it can be tolerated by the new ink delivery
system, alternative sealing arrangements could be used such as adhesives
and ultrasonic welding. In this preferred embodiment, the new IDS portion
97 is preferably moved into position in a direction substantially
perpendicular to a plane defined by the gasket sealing surfaces, as
depicted by FIG. 5C. New IDS portion 97 has a gasket 120 thereon that is
similar to the gasket structure discussed with respect to FIGS. 1B and
2A-2B. When the new IDS portion 97 is properly positioned in inner cavity
32, as indicated by FIG. SD, gasket 120 forms a compression seal between
portion 97 and receptacle 22. After positioning the new IDS portion 97, an
additional means of attachment may be used to secure new IDS portion 97 to
receptacle 22, such as the attachment features indicated in FIG. 1A, or
snaps, adhesives, rivets, crimp rings, screws, or other suitable means.
After attaching a new IDS portion 97, a flow of ink can be established
between an ink supply 70 (see FIG. 1) and printhead 20. The new IDS
portion 97, the ink supply 70, and any conduit 68 in-between, forms a new
ink delivery system (IDS). During a printing operation, the new IDS 100
provides pressure regulation in inner cavity 32 that enables stable
operation of printhead 20.
Although a particular way of disabling the old IDS 96 and connecting the
new IDS 100 was shown, other options are possible. For example, the old
IDS 96 is disabled to not provide ink to the ink delivery system, such as
by cutting off the flow of ink between the old ink supply 70 and inner
cavity 32. Next, an orifice 84 is formed in the side of receptacle 22 with
a process such as drilling and tapping. Next, a new IDS 100 is fluidically
coupled to the orifice. However, the gasket method described above is
advantageous because it does not require machining or damaging receptacle
22.
In FIGS. 5C and 5D, the new IDS portion 97 was generically shown, without
reference to a specific form of ink delivery system. This is because
portion 97 can be part of any number of IDS configurations as indicated by
FIGS. 6A-6C.
Usually, the same gasket seal area 92 (FIG. 5B) on the inner perimeter of
the inner cavity 32, where the gasket was seated for the original seal, is
used to form the new seal. However, one new sealing method might be to use
an adhesive 116, since in a low volume--no heat process, the previously
stated limitations of using an adhesive can be avoided. Similarly, if the
new IDS portion 97 replacement can tolerate it, the new IDS portion 97 and
printhead housing 36 can be sealed using ultrasonic welding. Generally,
the new IDS portion 97 will provide the ultrasonic welding features to
facilitate the welding process.
When the gasket 120 is engaged between the new IDS portion 97 and printhead
housing 36, as illustrated in FIG. 5D and attached using adhesive 116, the
same gasket or an identical replacement may be used to create a new seal.
However, a totally new type of gasket 120 or other type of sealant could
be used between the new IDS portion 97 and printhead housing 36, such as
an adhesive 116, another resilient member, or other sealant known to those
skilled in the art and still meet the spirit and scope of the invention.
Finally, the assembled inkjet cartridge 10 should be primed with ink and
any remaining air inside the printhead module purged. Several methods of
performing such steps are known to those skilled in the art.
Several methods of providing pressure regulation of the ink in an IDS are
available. A common type is to use capillary action such as that using
foam, for example Erturk et al., "Ink Retention in a Color Thermal Inkjet
Pen", Hewlett-Packard Journal, August 1988, pp.41-45. Another method is
active regulation in which a pressure valve opens and closes in response
to a pressure change in the printhead housing; see Cowger, "The
Optimization of Deliverable Ink from a Disposable Print Cartridge", IS&T's
Eighth International Congress on Advances in Non-Impact Printing
Technologies", 1992, pp.312-317. A simple method is to just provide
passive regulation where the height of the ink source relative to the
printhead level regulates the pressure. Those skilled in the art will
realize that other pressure regulating systems exist and still fall within
the spirit and scope of the invention.
Several embodiments of ink delivery systems (IDS), which can use gasket 120
and printhead housing 36, are now described that demonstrate the
usefulness of the invention.
FIG. 6A illustrates a first embodiment of an IDS that utilizes
electronically controlled pressure regulation and which includes an ink
supply 70, a electronically actuated valve 72, a pressure sensor 76, and
printing system control electronics 74. Pressure sensor 76 provides
signals to printing system control electronics 74 indicative of pressure
changes in printhead housing 36. Printing system control electronics 74
opens and closes valve 72 in response to regulate fluid pressure in
printhead housing 36.
FIG. 6B illustrates a second embodiment of an IDS which includes an ink
supply 70, a conduit 68, and a cover 28 used to couple the conduit 68
entering ink inlet 104 to the interior of the printhead housing 36. In
this second embodiment, a gravity regulated IDS, the pressure within
printhead housing 36 is regulated via the height difference 78 between the
printhead 20 and the ink supply 70 center of mass.
FIG. 6C illustrates a third embodiment of an IDS, referred to as a
removable IDS 82, such as illustrated in commonly assigned U.S. Pat. Nos.
5,642,144 and 5,680,164. In this embodiment, the IDS includes a resilient
sealing device, such as the gasket 120, to provide a perimeter seal
between the removable IDS 82 and the printhead housing 36. The removable
IDS 82 contains a reservoir to hold the ink and a regulator mechanism such
as foam, or spring bags, but other known regulator mechanisms could be
used and still meet the spirit and scope of the invention. A needle 130
mounted in printhead housing 36 punctures though a septum 118 in the
removable IDS 82 to allow the ink within removable IDS 82 to flow to the
printhead 20 through ink filter 134.
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